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Demonstration of the GRAVI3 technology – innovative gravity foundation for offshore wind

Periodic Reporting for period 2 - DEMOGRAVI3 (Demonstration of the GRAVI3 technology – innovative gravity foundation for offshore wind)

Reporting period: 2017-11-01 to 2018-12-31

Europe’s 2030 Energy Strategy has established a target to reduce greenhouse gas emissions by 40% compared to 1990 levels and renewable energy accounting for at least 27% of the energy consumed. In line with these targets, the European Wind Initiative (EWI) has established the objective of making offshore wind the most competitive energy source by 2030 and resulting in 150 GW of offshore wind capacity installed by 2030, which would represent about 12% of the EU electricity market. For this target to be attained it is essential that offshore wind expand to transitional waters (between 35 and 60 m depth). The GRAVI3 foundation concept will facilitate such a transition into deeper waters due to the efficient and cost effective structure in tandem with the economical transport and installation process. the offshore wind energy is a capital intensive industry, currently with a significant level of uncertainty, which negatively impacts the cost of capital and the cost of insurance. Additionally, the lack of standardization and scale also contributes to the high Levelized Cost of Energy (LCOE) for offshore wind.

In particular, the DEMOGRAVI3 project will demonstrate an innovative hybrid concrete-steel, self-buoyant bottom standing gravity based foundation (GBF) for offshore wind farms positioned in water depths between 35 and 60m. The complete unit (turbine and foundation) will be built and assembled onshore and towed while floating to the deployment site, where it will be submerged by an innovative patented process on a controlled way without the need for external support or heavy lift vessels. This project will demonstrate the following aspects: (A) Design, Fabrication and Assembly; (B) Transport and Installation, namely the submergence process; (C) Operation and Maintenance while supporting a working wind turbine; (D) Performance of the foundation and wind turbine vis-à-vis estimations; (E) Decommissioning and “post operation” analysis.
The overall goals of project DEMOGRAVI3 are: (1) To take the technology of the referred self-buoyant gravity based foundation concept from TRL 5 to TRL 7 (2) To demonstrate it is a technically viable solution to support offshore wind turbines, namely by confirming its performance estimates; (3) To demonstrate that this technology will attain an affordable LCOE in the medium term; (4) To demonstrate that this concept is a sustainable technology option to achieve the energy targets in the EU; (5) To create innovative and sustainable business models that maximize value creation while minimizing risks; (6) To further develop the technology for improved design, deployment and O&M; (7) To disseminate project results globally, namely opening its demonstration site for educational purposes, namely under the framework of the EUREC Master on Renewable Energy and KIC InnoEnergy Master on Energy Engineering and Management, and positioning Europe and European Institutions (Companies and Academia) as global leaders in offshore wind foundations
Having initiated in 1st January 2016, project DEMOGRAVI3 followed its normal implementation path, according to the plan. The project was initially suspended and later terminated, as an effect of the early withdrawal of one of the key partners, in charge of the construction of the caissons (a key element of DEMOGRAVI3) and the transportation and installation of the prototype (key activities). Despite the untimely termination of the project some very relevant outcomes resulted from project DEMOGRAVI3. Some of the most relevant are: (1) The detailed design of the DEMOGRAVI3 technology was entirely completed (WP2- Design & Engineering was successfully completed), allowing for a future revival and demonstration of this concept - this is a clearly exploitable result as this can still result in a promising and industry-relevant concept. The design activities included water tank tests of the operation, transportation and installation procedures (2 different sets of tests) as well as geothecnical and geophysical surveys to the installation site; (2) The metallic tripod, a very relevant part of the demonstrator, was almost entirely fabricated and assembled (the most important achievement of WP3) (3) All the preparation and planning work was completed not only from a technical perspective (assembly of the pieces was planned and laid out with detail, preparation of the transportation and installation was underway, fabrication of the caissons was entirely planned) but also from an administrative point of view, as the Portuguese electric and maritime permits were granted to the project (4) Dissemination and communication elements were all developed, including: Project Logo, Project website and social media, project dissemination leaflet. (5) A total of 5 articles/Thesis were produced in the scope of the project. The project was also displayed and promoted in several industry and trade fairs.
The technology's soundness was somewhat proved through the numerical simulations of the final design and the small-scale water tank tests carried out with good results. Once proved in full, the technology is likely to contribute to deliver a competitive and sustainable technology, targeting a total potential offshore wind market development in Europe between 2020 and 2030 with estimated capacity additions of 30 to 45 GW during this period. Additionally, and assuming a 30 to 40% of potential market share for self-buoyant GBF solutions in the same period (meaning around 11 to 16GW), equivalent to 1470 to 2130 high capacity (7+ MW) turbines / foundations, and up to 12,4 % of total EU wind capacity in 2014 (128,8 GW) and above the current offshore installed capacity (8,2GW). Furthermore, the annual share of EU 28 electricity consumption met by this targeted offshore wind capacity would be between 1,5% and 2,2%, using as possible reference 2,798 TWh final electricity consumption in 2012 (According to EWEA report, the most recent Eurostat available data, released in January 2015).
The technology is also likely to nurture the development of the industrial capacity to produce components and systems and opening of new opportunities in Europe, since the project includes the development of several activities in Europe (contributions to new codes and standards, Development of novel monitoring and inspection techniques applicable to other offshore technologies, just to name a couple). Moreover, DEMOGRAVI3 would help to strengthen the European industrial technology base, thereby creating growth and jobs in Europe, by leveraging on the fast growing offshore wind industry and contributing to foster European jobs with all activities concerning DEMOGRAVI3. Finally the project would have a very relevant impact in solving the global climate and energy challenges by contributing to increase the wind capacity in Europe.
CG Rendering of the Installation procedure of DEMOGRAVI3
Technical sketches and drawings of operations of DEMOGRAVI3
CG Rendering of the Transport procedure of DEMOGRAVI3
Fully fabricated pieces of the steel tripod, key part of the DEMOGRAVI3 prototype
Set of pictures showing the small-scale tank tests of DEMOGRAVI3 (2 different sets of tests)
Mockup of DEMOGRAVI3, once installed - view 1
Mockup of DEMOGRAVI3, once installed - view 2